The present invention relates to a connecting structure capable of accurately positioning an FPC terminal portion of a flexible printed circuit board mounted to a magnetic disk drive and a connector and being applicable to a base of a new structure.
A magnetic disk drive, which uses a base formed by pressing a steel plate, is provided with a flange for a sealing tape affixing surface on an edge of a base heretofore. The flange is formed substantially in parallel with the bottom of the base. A base cover is mounted over an upper surface of the base so as to be positioned inside the edge of the flange and thereafter the base cover and the flange are sealed using a sealing tape. Recently, in the course of pursuing a further reduction in size of the magnetic disk drive, a new enclosure structure has been proposed wherein the flange is removed for size reduction in the horizontal direction of the base and sealing tape affixing faces are formed sideways of the base.
FIGS. 7(A) to 7(C) illustrate a connecting structure of a flexible printed circuit board (hereinafter referred to as “FPC”) and a connector adopted in a conventional base 1 provided with a flange. FIG. 7(A) shows a bottom of the base 1 as seen from the outside or underside. A flange 3 is formed on an edge of the base 1. An FPC 5 is drawn out from an FPC draw-out port 14 formed in the base 1, and is connected to a spindle motor in the interior of the base 1. An FPC terminal portion 15 is formed at an extreme end of the FPC 5. The FPC terminal portion 15 is fixed temporarily to a terminal fixing portion 7 formed on the base 1 using a double-coated adhesive tape.
FIG. 7(B) is a plan view showing the temporarily fixed portion of FPC 5 on a larger scale. FIG. 7(C) is a side view showing a portion wherein a connector 9 is connected to the FPC 5. The terminal fixing portion 7 projects to a circuit board 11 side from the surface of the flange portion 3 so as to be suitable for connection with the connector 9 secured to the circuit board 11. A boss 8 projecting inside the base (the side opposite to the circuit board) is formed on the terminal fixing portion 7 by burring and the inside thereof is tapped for threaded insertion therein of a screw 13. In forming the boss 8, it has so far been taken into account that a tapping length should be ensured and that a plane for fixing the FPC terminal portion 15 cannot be ensured in the terminal fixing portion 7 if the boss 8 is projected to the terminal fixing portion 7 side. Moreover, a conclusive evidence that the boss 8 is positively utilized in positioning the FPC terminal portion 15 has not been obtained. For these reasons the boss has been projected inside the base.
The FPC draw-out port 14 is formed in the bottom of the base 1 as an elongated opening in conformity with the shape of FPC 5. In the structure for connecting FPC to the spindle motor, the FPC draw-out port 14 is disposed as in FIG. 7(B) with respect to a corner of the base 1. The FPC terminal portion 15 are formed with four terminal pads 6a, 6b, 6c and 6d which are connected to connector pins of the connector 9. The back side of the FPC terminal portion 15 is fixed to the terminal fixing portion 7 with use of a double-coated adhesive tape. Front end portions of the terminal pads 6a, 6b, 6c and 6d are later subjected to an insulating process because portions which have been used as electrodes in gold plating are exposed. In this case, to effect positioning of the connector 9 pre-fixed to the circuit board 11 and the FPC terminal portion 15, the edge 17 of the FPC terminal portion 15 is aligned with a boundary between the terminal fixing portion 7 and the flange 3 and also with an edge of the terminal fixing portion 7, followed by affixing with a double-coated adhesive tape. The positioning work has required skill because there has been no guide for positioning the FPC terminal portion 15 accurately relative to the base.
Since the longitudinal direction of the FPC draw-out port 14 and that of the terminal fixing portion 7 do not become parallel to each other due to the layout of the FPC draw-out port 14, the shape of the FPC 5 is improved so that the FPC terminal portion 15 is received within the terminal fixing portion 7. However, there is a difference in height between the FPC draw-out port 14 and the surface of the terminal fixing portion 7. Also, there is a slight error in the fixing position in the work of temporarily fixing the FPC terminal portion 15 to the terminal fixing portion 7. As a result, a deflection occurs in position A of the FPC 5. A restoring force of the deflection overcomes the adhesive force of the double-coated adhesive tape and causes a positional deviation of the FPC 5 in X or Y direction prior to fixing the connector 9 and the FPC 5 completely with a screw.
Moreover, the new base structure described above, in which a sealing tape is affixed to side faces of the base, requires that the side face of the base be utilized as a sealing tape affixing face. Thus, it is impossible to adopt such a conventional FPC terminal-connector connecting structure as forming a terminal fixing portion which utilizes the edge portion of the base. Therefore, it has been necessary to improve the connecting structure. Further, in adopting a new connecting structure, it has been necessary to solve the problem of alignment involved in the conventional connecting structure.
Patent Literature 1 (Japanese Patent Laid Open No. 2000-188487) describes an FPC cable whose shape is improved so that the connection of connector can be done within a narrow space and in a deflection-free state. For the connector connection disclosed in Patent Literature 1, an end portion of FPC cable matches an edge of a base.